East Indian sandalwood oil has heretofore been available only from East Indian sandalwood trees (age-60-80 years). This oil and various individual components of the oil are highly valued perfume bases and are used in large quantities by the perfume industry. The oil, however, is expensive and is in limited and sometimes sporadic, supply. For this reason, a continuous effort has been made to synthesize the various components of sandalwood oil or similar synthetic materials which possess odors similar to the desirable woody fragrance of sandalwood oil.
Synthetic bicyclo(2.2.1) heptanes and the processes for preparing these compounds represent a portion of an extensive scientific effort to prepare compounds having the valuable characteristics of sandalwood. Other processes and compounds relating to the synthesis of synthetic sandalwood oil components are described in the following U.S. Patents:
i. Perfume Compounds And Process For Preparing Same U.S. Pat. No. 3,673,261 issued June 27, 1972: Compounds: ##STR14## ii. Dihydro-beta-santalol and Processes For Preparing Dihydro-beta-Santalol From 3-Endo-Methyl-3-Exo(4'-Methyl-5'-Hydroxyphenyl) Norcamphor -- U.S. Pat. No. 3,673,263 issued June 27, 1972: ##STR15## iii. Process For Preparing Beta-Santalol From 3-Methylnorcamphor -- U.S. Pat. No. 3,662,008 issued May 9, 1972: ##STR16## iv. Process For Preparing Dihydro-Beta-Santalol From 3-Endo-Methyl-3-Exo(4'-Methyl-5'-Hydroxypentyl) Norcamphor -- U.S. Pat. No. 3,673,266, issued June 27, 1972: ##STR17## PA1 I. subjecting oil of turpentine to an intense oxidation step comprising continuously insufflating air through said oil at a temperature of about 70.degree. C while agitating said oil and irradiating said oil with ultraviolet light in the presence of: PA1 Ii. distilling off the reaction products having a boiling point of about 75.degree. C at 10 mm Hg; and PA1 Iii. rectifying the distilled reaction products collected, is disclosed. PA1 I. subjecting one or more hydrocarbon compounds represented by the structure: ##STR48## to an intense, oxidation step which comprises continuously insufflating air through said hydrocarbon compound, while agitating said hydrocarbon compound, and exposing said hydrocarbon compound to ultra violet light in the presence of a catalyst comprising an alkaline metal hydroxide and rose bengal; and PA1 Ii. fractionally distilling the resulting reaction products. PA1 I. reacting one or more hydrocarbon compounds represented by the structure: ##STR50## with a peracid selected from the group consisting of peracetic acid and perbenzoic acid at a temperature in the range of from -10.degree. C up to +20.degree. C and in the presence of an inert solvent and an alkali metal alkanoate and PA1 Ii. fractionally distilling the reaction product. PA1 I. reacting one or more of the epoxide compounds produced according to Process B with lithium aluminum hydride in the presence of an inert solvent; and PA1 Ii. fractionally distilling the resulting reaction products. PA1 I. reacting one or more of the epoxide compounds, produced according to Process B having the structure: ##STR53## with lithium aluminum hydride and III. Fractionally distilling the resulting reaction products. PA1 I. reacting one or more of the epoxide compounds, produced according to Process B having the structure: ##STR55## with diphenyl diselenide and sodium borohydride; and II. Fractionally distilling the resulting reaction products. PA1 I. reacting one or more of the epoxide compounds, produced according to Process B having the structure: ##STR57## with aluminum isopropoxide, the ratio of aluminum isopropoxide: reactant being about 1:10; PA1 Process "A" may be carried out using as a reactant a mixture of alpha-santalene, beta-santalene and epibeta-santalene or the individual compounds, produced either (i) synthetically per examples B, C and D infra or (ii) by means of distillation of saponified sandalwood oil according to example A infra.
In addition, a relatively large quantity of investigative work has been carried out concerning photochemistry in the field of monoterpenes and related compounds. Thus U.S. Pat. No. 3,673,066 concerns a process for the preparation of verbenone, myrtenol, myrtenal, trans-verbenol, cis-verbenol, pinocarbeol, alpha-pinene epoxide and campholene aldehyde comprising:
a. From 0.05 to 0.5 percent by weight of a promoter selected from the group consisting of organic salts and complexes of nickel, vanadium, tungsten, tantalum, niobium, rhenium, tellurium and selenium, and PA2 b. In the presence of from 1 to 10 percent by weight of at least one catalyst selected from the group consisting of:
1. The abietates, the levopimarates, the dextropimarates and the pinonates of cobalt, manganese and nickel; and PA3 2. A member selected from the group consisting of the acetylacetonates, the phthalocyanines and the terpenic acid salts of nickel, cobalt, vanadium, tungsten, tantalum, niobium and rhenium; the oxides of selenium and tellurium; the naphthenates, the oleates, and the stearates of cobalt, manganese and nickel; in the presence of from 0.05 to 0.5 percent by weight of at least one member selected from the group consisting of copper (II) salts, cesium salts and mixtures thereof;
A paper by Michel Pfau entitled "Photochemistry in the Field of Monoterpenes and Related Compounds" (The Flavour Industry, February, 1972, Page 89-103) discloses, interalia the following reaction sequence: ##STR18##
The compounds described and processes described and the above cited prior art do not suggest the compounds and processes of the instant invention. Indeed nothing in the prior art sets forth such strong sandalwood fragrances as the compounds of the instant invention and no process in the prior art teaches such a commercially feasible process as is set forth herein.
Thus, a complex multi-step process for producing the compound having the structure: ##STR19## is taught by Colonge et al., Bull.Soc.Chim.France 1966, pp. 374-376 ("Synthese de Santatols") and a complex process for producing compounds having the generic structure: ##STR20## is taught in U.S. Pat. No. 3,390,197.